1. Field of the Invention
The invention relates generally to an apparatus for processing wafer-shaped articles, such as semiconductor wafers, and more particularly relates to such an apparatus comprising a spin chuck and a rotating gas showerhead.
2. Description of Related Art
Semiconductor wafers are subjected to various surface treatment processes such as etching, cleaning, polishing and material deposition. To accommodate such processes, a single wafer may be supported in relation to one or more treatment fluid nozzles by a chuck associated with a rotatable carrier, as is described for example in U.S. Pat. Nos. 4,903,717 and 5,513,668.
Alternatively, a chuck in the form of a ring rotor adapted to support a wafer may be located within a closed process chamber and driven without physical contact through an active magnetic bearing, as is described for example in International Publication No. WO 2007/101764 and U.S. Pat. No. 6,485,531.
It is known to equip such chucks with a gas showerhead so as to introduce a controlled atmosphere adjacent a surface of the wafer undergoing processing on the chuck. Examples of such showerheads are shown in commonly-owned copending application US 2014/0026926 and commonly-owned U.S. Pat. No. 8,926,788. However, depending upon the type of chuck and the type of surrounding structure, it can be difficult to maintain a desired atmosphere and it can also be difficult to utilize process gas efficiently with conventional gas showerheads.